There was a rending crash of metal that seemed to split the air beneath us, and then in a great shower of wrecked and twisted cruisers the ships beneath were falling, tumbling down and vanishing into the vapors far beneath on their headlong fall toward the Atlantic! All of the twenty enemy cruisers, and about twenty-five of our own four-score that had crashed down into them, fell thus, annihilated almost by that terrific collision. It had been the one means, though, of instantly destroying their patrols without using our heat-guns whose detonations might give the alarm. And we knew that only that swift, unordered action on the part of our lowest ships had saved us. Then the fifty-five survivors had rushed up again among us, and then our ships that had slowed there for the moment were rushing still on eastward. The Air-Forts Onward we shot through the upper night, shaken still by that sudden peril and escape, and then I uttered a warning word into the distance-phone from our cruiser leading. For now, far ahead, we could make out great beams of white light that hung in a great row extended from north to south as far as the eye could reach, and that seemed like white fingers of light whirling and reaching through the air as they ceaselessly swung and circled. A full four miles above the earth, and more than that beneath the level of our own onrushing ships, hung this great line of restless beams, and we knew it, at once, for the great line of air-forts that guarded the western approaches of the European Federation. For the beams we saw were the great beams of the air-forts' mighty searchlights, and those swinging shafts of radiance were of such intense brilliance and magnitude that even at our greatest flying height we could not hope to pass over them undetected. It seemed, indeed, that to pass them was hopeless, since the air-forts, hanging above the great layer of misty vapor that stretched beneath, could instantly detect with those mighty beams any cruisers passing above them, at whatever height, and could blast them from the air with their gigantic batteries of heat-guns. To pass beneath the great vapor-layer was as impossible, since the air-fort chain which the European Federation put forth here in war-time was a double one, and its second line hung, farther eastward a little, beneath the vapor area, watching with its own great beams and guns for any ships passing there. There remained but one alternative, to pass through the thick mists of the vapor-layer itself, but that, though concealing us from the guns of air-forts above and beneath, would be in itself suicide, since such vapor-layers between the forts were invariably filled in war-time with floating air-mines, great cube-like metal containers held aloft and motionless by their own electrostatic-motors and tube-propellers and which contained a terrific heat-charge which was instantly released upon any luckless ship that touched them.